Alkyl beta-(n&#39;-2-tetrahydropyranylureido)acrylates

ABSTRACT

NOVEL 1,2,3,4-TETRAHYDROPYRIMIDINE-2,4-DIONES OF THE FORMULA   3-((-(CH2)N-O-)&gt;CH-),5-R2,6-R1-1,2,3,4-TETRAHYDRO-   PYRIMIDINE-2,4-DIONE   WHEREIN R1 IS SELECTED FROM THE GROUP CONSISTING OF LOWER ALKYL OF 1 TO 7 CARBON ATOMS AND PHENYL, R2 IS SELECTED FROM THE GROUP CONSISTING OF HYDROGEN, CHLORINE, BROMINE AND LOWER ALKYL OF 1 TO 7 CARBON ATOMS AND N IS 3 OR 4 WHICH HAVE HERBICIDAL ACTIVITY AND THEIR PREPARATION AND INTERMEDIATES THEREFOR.

i 3,808,235 ALKYL fl-(N'J-TETRAHYDROPYRANYLURHDO) ACRYLATES DanielBertin, Jacques Perronnet, and Andre Teche, Paris, France, assiguors toRoussel-UCLAF, Paris, France No Drawing. Original application Mar. 22,1971, Ser. No.

126,865, now Patent No. 3,732,228. Divided and this application Sept.21, 1972, Ser. No. 290,965

Int. Cl. C07d 7/04 US. Cl. 260-345.8 6 Claims Novel1,2,3,4-tetrahydropyrimidine-2,4-diones of the formula wherein R isselectedfrom the group vconsisting of'lower alkyl of 1 to 7 ,carbonatomsand-phenyl, R is selected y from the group consisting of. hydrogen,chlorine, bromine and lower alkyl of 1 to 7 carbon atomsand n is .3, or4 which have herbicidalactivity andtheir preparationrand intermediatestherefor.

Y PRIOR APPLICATION This application is a division of our copending,commonly assigned US. patent application, Ser. No. 126,865, filed Mar.22,-1971,,now U.S.- Pat. N0.i3,732,228.

STATE OF THE ART Certain tetrahydropyrimidines are known to possessherbicidal activity. For-example, 3-sec.butyl-5 bromo-6-methyl-1,2,3,4-tetrahydropyrimidine-Z,4-dione, sold under the, namebromacile, is used for eradicating weeds in orchards of adult peachtrees. Unfortunately, these compounds'cannot be generally used except astotal'herbicides as their activity is not selective.

OBJECTS OF THEJNVENTION It is an object of the invention to.providee-the .novel 1,2,3,4-tetrahydropyrimidinee2,4ediones of FormulaI.

I It is another, object of theinvention toprovide a novel process forthe preparation of the compounds ofFormula I and to provide the novelintermediates .formed in said 1, process.

It is an object of the invention to providecnovelherbicidal compositionsand. totprovide a novel method of killing undesired plants.

These and other objects and advantages of the invention will becomeobvious from the following detailed description.

, THE INVENTION The novel i 1,2,3,4-tetrahydropyropyrimidine-2;4-dionesofrthe invention havethe formula 1 is se sq e f th ount qn istinsqfilqwy f 1 to,7. q rb n at a r eny R2 i se ect d United States Patent3,808,235 Patented, Apr. 30, .1974

from the group consisting of hydrogen, chlorine, bromine and lower alkylof 1 to 7 carbon atoms and n is 3 or 4.

Examples of suitable compounds of Formula I are3-(2'-tetrahydropyranyl)-5-bromo-6-phenyl-l,2,3,4-

, tetrahydropyrimidine-2,4-dione. The novel process of the invention forthe preparation of the tetrahydropyrimidincs of Formula I comprisescondensing an alkyl ,B-amino-acrylate of the formula v wherein R and Rhave the above definitions and All; is

lower-alkyl of 1 to 7 carbon atoms with an isocyanate selected from thegroup vconsisting of 2-tetrahydropyranyl isocyanate and2-tetrahydrofuranyl isocyanate in the presence of .a basic agent to forman alkyl p-(N- 2-tetra hydroheteroc'yclic ureido)-acrylate of thetormula Alli-00C (III) wherein R R Alk and n have the above definitionsand cyclizing the latter in the presence of a basicagent. to form thecorresponding compound of Formula I.

Preferably the basic condensation agent is a tertiary I amine such astrimethylamine, tri ethylamine, pyridine,,N-

methyl-piperidine, N-methyl-pyrrolidine or quinoline, The basiccyclization agent is preferably an alkali meta l lower alcoholate suchas sodium methylate or sodium ethylate.

"The cyclization is preferably efiected inan organic solvent'such as analcohol, e.g. ethanol. I Thestarting alkyl fi-amino acrylates of FormulaII can be prepared from a compound of the formula 0 Rh 0 Rriii-H-ELOAU!-(IV) wherein R R and Alk have the above definitions by a processanalogous to that. described by Gen-vresse (Ann. de,Chim.,.vol. 24, p.64). Z-tetrahydropyranyl isocyanate may be prepared by the processdescribed in French Pat.

No. 1,425,137 and Z-tetrahydrofuranylisocyanate may be prepared byreacting 2-chloro-tetrahydrofuran with acetonitrile.

- The process of the invention comprises 2 stages, the

-- condensationand the cyclization. The intermediate resultingfrom thecondensation step may be recovered and purified and then cyclized orthey cyclization may be effected in the reaction mixture resulting fromthe condensation.

In a variation of the process of the invention, the compounds of FormulaIII may be prepared by condensing in the presence of a dehydration agentan alkyl B-ureidoacrylate of the formula chlorine or bromine, thecorresponding compound of Formula I where R is hydrogen is reacted witha halogenation agent. Suitable halogenation agents are sulfuryl chloridewhere R is to be chlorine and bromine or N- bromo-succinimide when R isto be bromine.

The compounds of Formula I present little or no phyto toxic activityagainst certain valuable plants such as cotton and can therefore be usedto kill parasitic weeds in fields of the useful plants. The saidcompounds have preand post-emergence herbicidal activity as can be seenfrom tests against large botanical families such as foxtail grass,Chrysanthemum, flax, mustard, oats, wheat, corn,clover and beets.

The novel herbicidal compositions of the invention are comprised of atleast one compound of Formula I and an inert carrier. The compositionsmay be in the form of 1 powders, granules and suspensions, emulsions orsolutions containing the active ingredients, for example a mixture witha vehicle and/or an anionic, cationic or non-ionic surface active agentto insure a uniformdispersion of the substances in the composition. Thevehicle may .be a liquid such as water, alcohol, hydrocarbons or otherorganic solvents, a mineral, animal or vegetable oil or a powder such astalc, kieselguhr, silicates or clay.

The solid compositions in the form of a dusting powder, wettable powderor granules may be prepared by grinding the active compound with aninert solid or by impregnation of a solid support with a solution of theactive ingredient in a solvent and evaporating the solvent. Thecompositions may contain other active agents such as other pesticides,herbicides, and/or fungicides, biocides, insecticides, etc., and othercompounds influencing the growth of the plants.

The novel process of killing weeds comprises contacting weeds with aherbicidal amount of at least one compound of Formula I either before orafter emergence of the weeds. The usual useful amount of the activecompound is 0.2 to 40 kg./ha. and preferably 0.6 to 5.0 kg./ha. Theexact amount will vary as a function of treated vegetation, the natureof terrain, atmospheric conditions and state of growth.

In the following examples here are described several preferredembodiments to illustrate the invention. However, it should beunderstood that the invention is not intended to be limited to thespecific embodiments.

EXAMPLE I Preparation of 3-(2-tetrahydropyranyl)-5,6-dimethyl-1,2,3,4-tetrahydropyramidine-2,4-dione A'mixture of 42.9 g. of ethyl2-methyl 3 amino-- crotonate in 600 cc. of toluene, 52.5 g. of2-tetrahydropyranyl isocyanate and 42 cc. of triethylamine was refluxedfor 17 hours and was then cooled to 20 C. The mixture was introduced into a solution of 60 g. of sodium methylate in 300- cc. of ethanol andthemixture was progressively heated to reflux and held there for 3Ominutes. After cooling to 20 C, 300 cc. of water were added thereto andthe organic phase was decanted 01f. The aqueous phase was extracted withether and then the pH was the literature.

EXAMPLE II Using the procedure of Example I, ethyl 2-chloro-3-amino-crotonate and 2-tetrahydrofuranyl-isocyanate were reacted to form3-(2'-tetrahydrofuranyl) 5 chloro-6-methyl-1,2,3,4-tetrahydropyrimidine-2,4 dione melting at 200 C.

LAS far as is known, this compound is not described in the literature.

The 2-tetrahydrofuranyl-isocyanate is prepared as follows:

A mixture of 75 g. of 2-chloro-tetrahydrofuran [prepared by method ofNormant, C. R., vol. 228 (1949), p. 102], 150 cc. of anhydrousacetonitrile, 150 cc. of anhydrous benzene and 70 g. of sodium cyanatewas held at a temperature of 3538 C. for 2 /2 hours and then wasrefluxed for 10 minutes and then was cooled. The insoluble precipitatewas removed by vacuum filtration and the solvents were evaporated offunder reduced pressure and rectification gave 40 g. ofZ-tetrahydrofuranyl isocyanate having a melting point of 60 C. at 35 mm.Hg.

As far as is'known, this compound is not described in the literature.

EXAMPLE I'H Preparation of 3 (2'-tetrahydropyranyl) -6-methy1- v1,2,3,t-tetrahyclropyrimidine-2,4-dione A mixture of 30 g. of ethyl3-amino-crotonate, 75 cc. of anhydrous toluene, 15 g. of triethylamineand 30 g. of 2-tetrahydropyrany1 isocyanate was refluxed under anitrogen atmosphere for two hours and the resulting'solution was cooledto room temperature and then was added to 150 cc. of ethanol and 30 g.of sodium methylate. The reaction mixture was refluxed for one hour andthe solution was then concentrated to about cc. After addition to water,the mixture was washed with methylene chloride. The resulting aqueousphase was concentrated, acidified to a pH of 2 bythe addition ofhydrochloric acid and was then vacuum filtered to obtain 26 g. of 3-(2'- tetrahydropyranyl)-6-methyl 1,2,3,4 tetrahydropyrimidine-2,4-dionemelting at 224 C.

As far as is known, this compound is not described in the literature.

EXAMPLE IV Preparation of 3-(2'-tetrahydropyranyl)-5-ch1oro-6-methyl-1,2,3,4-tetrahydropyrimidine-2,4-dione Step A.Ethyla-chloro-B-ureido-crotonate: A mixture of g. of ethyla-chloro-acetylacetate [prepared by method of Allihn, Ber., vol.'11(1878), p. 567], 60 g. of urea and a few cc. of pure hydrochloric acidwas heated with agitation at 5055 C. for 16 hours at a pressure of 80mm. Hg. After cooling the reaction mixture, the precipitate wasrecovered by vacuum filtration and washed with ether and then water toobtain 37 g. of ethyl u-ChlO- ro-fi-ureido crotonate melting at 181 C.

As far as is known, this compound is not described in the literature. 1

Step B.'Ethyl B -(N'-2 tetrahydropyranyl-ureido)-mchlorocrotonate: Amixture of 25 g. of ethyl oz-ChlOIO-flureido-crotonate, 12.5 g.'ofdihydropyran and 2 g. of ptoluenesulfonic acid in 650 cc. oftetrahydrofuran was refluxed with agitation for 4 hours and aftercooling, 500

cc. of ethyl acetate were added thereto. The mixture was washedwith/water, dried. over magnesium sulfate and then evaporated to drynessunder reduced. pressure; The oily residue'. was crystallized fromisopr'opyl ether to ob+ tain g. of ethyl-,B-(N-2-tetrahydropyranyl-ureido)-uchlorocrotonate melting at 107 C.

As far asis known, this compound is not described in the literature.

Step C.'3 (2'-tetrahydropyranyl)-5-chloro-6-methyl-1,2,3,4-tetrahydropyrimidine-2,4-dione: 25 g. of ethyl 13- (N'Z-tetrahydropyranyl-ureido') -a-chlorocrotonate were added all at onceto a solution of 25 g. of sodium meth ylate in 250 cc. of ethanol andthe mixture was refluxed for 30 minutes-and was then evaporated todryness under reduced pressure'. The oil formed Was dissolved in waterand the solution was acidified by the addition of pure hydrochloricacid. The precipitate formed was recovered by vacuum filtration toobtain l5-g. of 3-(2'-tetrahydropyranyl)-5-chloro-6-methyl 1,2,3,4'tetrahydropyrimidine-2,4-dione melting at 225 C. A sample of the prodnot after crystallization from ethyl acetate was analyzed as follows:

Analysis.-C H ClN O3: molecular weight=244.68. Calculated (percent): C,49.08; H, 5.36; CI, 14.49; N, 11.45. Found- (percent): C, 49.2; 'H,5.20; Cl, 14.7; N, 11.3.

As far as is known, this compound is not described in the literature.

EXAMPLE V 3-(2 -tetrahydropyranyl) -5-chloro-6-methyl-1,2,3,4-

. tetrahydropyrimidine-2,4-dione EXAMPLE VI .Preparation of3-(2'-tetrahydropyranyl)-5-bromo'-6-methyl-1,2,3,4-tetrahydropyrimidine-2,4-d1one 24 g. of3-(2'-tetrahydropyranyl) 6 methyl-1,2,3,4-tetrahy'dropyrimidine-2,'4-dione were addedto a solution containing 25g. of N-bromosuccinimide -and'250 cc.--of carbon tetrachloride and thesolution was refluxed for '90 minutes. After cooling to roomtemperature, 250 cc. of methylene chloride were added to-the mixturewhich was then washed with water, dried over sodium sulfate, filteredand' evaporated to dryness under reduced pressure. Theresidue wascrystallizedfrom ethanol to ob tain 16 g. of'3-(2'-tetrahydropyranyl)-5-bromo-6 methyl-1,2,3,4-tetrahydropyrin1idine-2,4-dionemelting-at 210 C. Analysis.--C HBrN O molecular weight=289. l4. Calculated (percent): C, 41.54; H, 4.53;Br, 27.64; N, 9.69. Found (percent): C, 41.9; H, 4.8; Br, 27.9; N, 9.6.As far as is known, this compound is not described in the literature.

EXAMPLE VII Preparation of 3-(2'-tetrahy.drofuranyl)-5 bromo-6-methyl-1,2,3,4-tetrahydropyrimidinc-2,4-dione StepA.3-(2-tetrahydrofuranyl) 6 methyl-1,2,3,4-tetrahydropyrimidine-2,4-dione: 46' g. of 2-tetrahydrofuranyl isocyanatewere added under nitrogen to a solu-. tion containing 46 g. of ethyl3-amino-crotonate, 12.8 g. of triethylamine and 90 cc. of anhydroustoluene and the mixture was refluxed for 90 minutes and then was cooled6 to room temperature. 35.5 g. of sodium methylate and 180 cc. ofethanol werefadded to the reaction mixture and the resulting solutionwas refluxed for l'hour and then evaporated. to dryness under reducedpressure. The yellow oil residuewas'dissolved in 200 cc. of water andthe solution was washed with 40 cc. of methylene chloride and evaporatedto dryness under reduced pressure. The residue was dissolved ini100 cc.of water and the'solution was made slightly. acidic by addition ofconcentrated by drochloric acid. The resulting precipitatewas'reco-vered by vacuum filtrationand was dissolved in methylenechloride. The organic solution was dried over sodium sulfate; filteredand evaporated to dryness under reduced pressure, The residue wasempasted with ethyl ether to obtain 25 g. of 3-(2'-tetrahydrofuranyl)-6-methyl 1,2,3,4-tetrahy dropyrimidine-2,4-dionemelting at 202 C.

Analysis.---C H N O molecular weight= l96.19. Cal-I culated (percent):C, 55.09; H, 6.17; N, 14.28.,Found (percent): C, 55.1; H, 6.3; N, 14.3.I As far as is known, this compound is not described in the literature.i I I Step B.3-(2-tetrahydrofuranyl)-5-brorno -.6 methyl-1,2,3,4-tetrahydropyrimidine-2,4-dione: 28 g'. of N-bro mosuccinimidewere added to a suspension containing 31 g. of3-(2'-tetrahydrofuranyl)-6-methyl-1,2,3,4 tetrahydropyrimidine'-2,4-dione and 300 cc. of carbon tetrachloride. Theresulting suspension wasrefluxed with agitation for 1 hour and thencooled to room temperature. 600 cc. of methylene chloride were added tothe reaction mixture which was then Washedtwice with 300 cc. of water,dried over sodium sulfate, filtered and evaporated to dryness underreduced pressure. The resulting white crystalline product wascrystallized-from ethanoltoobtain 24 g. of 3-(2' tetrahydrofuranyl) 5bromo 6 methyl-1,2,3,4- tetrahydropyrimidine-2,4-dione melting at 185 C.Analysis.C H BrN O molecular weight=275.08.- Calculated (percent): C,39.30; H, 4.03; N, 1019; Br, 29.05. Found (percent): C, 39.7; H, 4.1;.N,9.8; Br, 29.1. As far as is known this'compound is not describedin theliterature;

EXAMPLE vnr 0.57 cc. of sulfuryl chloride were added to a solution of1.2 g. of 3 -(2-tetrahydrofuranyl)- 6-rnethyl-1,2,3,4-

under reduced pressure to obtain 1. g. of white product which wascrystallized-from ethanol to obtain 0.5 g. of

3-(2-tetrahydrofuranyl) 5 chloro 6 methyl 1,2,3,4-tetrahydropyrirnidine-2,4-dione melting at 200 C. The product wasidentical to that of Example II.

Analysis.---C H ClN O molecular weight=230.63; Calculated (percent): C,46.86; H, 4.81; N,'12.l5;-Cl, 15.38. Found (percent): C, 46.6; H, 4.8;N, 12.5; C1, 15.1.

EXAMPLE 1X Preparation of 3'-(2'-tetrahydropyranyl) -6-phenyl-1,2,3,4-tetrahydrOpyrimidine-Z,4-dione Step A.-Ethyl fi-(N-2-tetrahydropyranyl-ureido)-ac rylate: 71 g. of ethylfi-phenyl-fi-amino-acrylate (prepared by method of Lukes et' al., C. A.,vol. 54 (1960), p. 11984e) and 3 cc. of triethylamine were added to 200cc. of toluene, and then 66.9 .g. of 2-tetrahydropyranyl isocyanate andcc. of anhydrous toluene were added to the reaction mixture. The mixturewas refluxed for 12 hours and the toluene was distilled off underreduced pressure. The yellow oil residue was, takenup in 100 cc. ofabsolute ethanol to obtain 216.5 g. of an alcoholic solution of ethylfl-(N'-2-tetrahydropyranyl-ureido)-acrylate.

As far as is known, this compound is not described in the literature.

Step B.3-(2'-tetrahydropyranyl) 6 phenyl-l,2,3 ,4-tetrahydropyrimidine-2,4-dione: A mixture of 144 g. of the alcoholicsolution of Step A and 15 g. of sodium ethylate in 150 cc. of absoluteethanol was refluxed for 12 hours and then evaporated to dryness underreduced pressure. The solid residue was taken up in 250 cc. of ether andthe solution was filtered and the solid was washed twice with 50 cc. ofether. The solid obtained was dissolved in 1 liter of water and thesolution was adjusted to a pH of 4 by addition of concentratedhydrochloric acid. The precipitate was recovered by vacuumfiltration andwas empasted 3 times with isopropyl ether and vacuum filtered to obtaina white product. The said product was crystallized from 18 volumes ofisopropanol to obtain 17 g. of3-(2'-tetrahydropyranyl)-6-phenyl-1,2,3,4-tetrahydropyrimidine-2,4-dione.meltingat 235 C.

Analysis.C H N O molecular weight=272.30. Calculated (percent): C,66.15; H, 5.92; N, 10.25. Found (percent): C, 66; H, 6.1; N, 9.9. i

As far as is known, this compoundis not described in the literature.

EXAMPLE X 3-(2-tetrahydropyranyl)-5-chloro 6-phenyl-1,2,3,4-

tetrahydropyrimidine-2,4-dione 2.7 g. of3-(2'-tetrahydropyranyl)'-6-phenyl1,2,3,4-tetrahydropyrimidine-2,4-dione of Example IX were added to 30 cc. ofchloroform and then 1.3 cc. of sul-furyl chloride and 20 cc. ofchloroform were added to the mixture at C. The reaction mixture wasstirred at 0 C. for 45 minutes, and the resulting'solution was added toan aqueous sodium carbonate solution. The decanted chloroform solutionwas washed with 100 cc. of water, was dried over sodium sulfate,filtered and evaporated to dryness under reduced pressure. The residuewas taken up in isopropyl ether and the product obtained by filtrationthereof was crystallized from isopropyl alcohol and then from ethylacetate to obtain 1.1 g. of 3-(2'-tetrahydropyranyl)- -chloro 6phenyl-1,2,3,4-tetrahydropyrimidine-2,4-dione melting at l94196 C.

Analysis.C H ClN O molecular weight=306.751. Calculated (percent): C,58.73; H, 4.13; CI, 11.56; N, 9.13. Found (percent): C, 58.8; H, 5.1;C], 11.4; N, 8.8. As far as is known, this compound is not described inthe literature.

EXAMPLE XI Preparation of 3-(2'-tetrahydropyranyl)-5-bromo-6-phenyl-1,2,3,4-tetrahydropyrimidine-2,4-dione A mixture of 1.75 g. ofN-bromosuccinimide and 2.7 g. of 3(2'-tetrahydropyranyl)-6-phenyl-1,2,3,4-tetrahydropyrimidine-2,4-dionein 100 cc. ofjcarbon tetrachloride was refluxed for 1 hour, then wascooled and 200 cc. of water were added thereto. The organic layer wasseparated by decanting and was washed with 200 cc. of water, dried oversodium sulfate, filtered and evaporated to dryness under reducedpressure. The yellowish white residue Y 8 HERBICIDAL ACTIVITY Oats,clover, beets, wheat, corn flax, mustard, crysanthemum and foxtailgrasswere cultivated in a double bottom box (23 x 14 x 4 cm.) withWetting from underneath. 20 seeds of each species were placed in rows 3cm. apart in one box and 4 repetitions were used for each concentration.The following culture conditions were observed: temperature of 20 C.i2,about 60% humidity, fluorescent tube light (light of day+brilliantwhite) for 16 hours each day. The soil mixture used was 10 volumes ofriver-sand, 10 volumes of arable soil and 2 volumes of peat. v 4

'For the pre-emergence test, the treatment was effected 24 hours afterthe seeding and the first wetting was efe fected by aspersion culture toentrain'a part of the prod: net to the level of the seeds. For the postemergence test, the treatment was effected after 21 days of growth withthe above ground parts.

In both cases, the test compounds were applied in standard compositionswith a micro-pulverizer at doses corresponding to 5, 2.5, 1.25 and 0.62kg./ha. at a dilution corresponding to 560 liters per ha. The testcontrols were subjected to the same treatment without the activecompounds. The final control was effected by weighing the plants 21 daysafter treatment in thepre-emergence test and 15 days after treatment inthe post-emergence test and the results'were expressed as percentage('P) of reduction of vegetation as follows: w

weight of control plants-weight of treated plants weight of controlplants p I The following tables report the results with3-(2-tetrahydropyranyD-S-chloro 6 methyl 1,2,3,4tetrahydropyrimidine-2,4-dione (Compound A) and the commercialpreemergence herbicide, Atrazine,(2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) or the postemergence herbicide, Linuron [N'-(3,4-dichlorophenyl)-N-methoxy-N-methylurea.]

TABLE I.PRE-EMERGENCE 7 Compound A Atrazlne Kg. MA/ha .L 5.0 2. 5 1. 250. 62 5. 0 2.5 1. 25, o. 52

Cats 100 65.0 45.0 100 Beets 100 100 Wheat 100 78 0 55.0 22.0 67.0 64.050.0 50.0 Chrysanthemum. 100 100 Flax 100 94.0. 84.0 100 Corn 65.0 45 017.0 11.0 0 0 0 0 Mustard 100 100 Clover 100 100 Foxtail grass 100 100TABLE II.POST EMERGEN CE Compound A Linuron Kg. MA/ha 5.0 2.5 1. 25 0.62 5. 0 2. 5 1. 25 0 62 Oats 100 100 Beets 100 100 Wheat 100 100 55. 060 0 Chrysanthemum 100 100 lax 100 100 Corn 30. 0 31. 0 20. 0 15. 0 65.0 30. 0 '20; 0 5. 0 Mustard 1-. 100 100 Clover 100 100 Foxtall grass 10085. 0 100 40. 0 60. 0

7 Tables I1I-and IV show the results of preand post emergence tests with3-(2'-tetrahydropyranyl)-5-bromos 6-methyl 1,2,3,4tetrahydropyrimidine-2,4-dione (Com pound B).

TABLE III.-P RE EMERGENCE Kg. MA/ha 5 2.5 1.25 0.62

Oats 100 100 Y 69 61 Wheat 67 64 63 2O Corn .t ,0 0 0 0 Foxtail gras's100 100- 100 Y 88 Beets 100 100 100 I 100 Chrysanthemum 100 100 100 '100lax 100 100 -100 Mustard 100 100 100 Clover 100 100 100 .44

TABLE IV.--POST EMEHGENCE Various modifications of the compositions andmethod of the invention may be made without departing from the spirit orscope thereof and it is to be understood that the invention is to belimited only as defined in the appended claims.

We claim:

1. A compound of the formula wherein R is selected from the groupconsisting of hydrogen, methyl and chlorine and n is 4.

10 2. A compound of claim 1 wherein R, is chlorine and n is 4.

3. A compound of claim 1 wherein R, is methyl and n is 4.

4. A compound of claim 1 wherein R is hydrogen and n is 4.

5. A compound of the formula /C=O\ 0 (CH1).

wherein Alk is alkyl of 1 to 7 carbon atoms and n is 4. 6. A compoundof'claim 5 wherein Alk is ethyl and n is 4. i z

References Cited UNITED STATES PATENTS 3,658,819 4/1972 Bertin et a1.260-3458 NORMA S. MILESTONE, Primary Examiner

